2. Animations Android platform provides 2 kind of animations:
View Animation: the old system that allows you to apply animations
on View. Property Animation: the new system introduced by Android
3.0 HoneyComb that applies animation to the properties of any
object. The use of property animation is recommended because they
are more flexible and have more features. The Android framework
provides besides the above systems, the ability to create Drawable
Animation: the animation is achieved by successive display of
drawable resources. Animation Frameworks
3. Animations The animation is applied to the entire view
including the background. N.B. The limits of View will remain
unchanged Possible transformations are: Positions: translate
Dimensions: scale Rotations: rotate Opacity: alpha The sequence of
these transformations can be declared as a resource in the
/res/anim file as xml or in code. Animations can be sequential
and/or concurrent. The attributes to be included or are common to
all the animations or specific type of animation. View Animation -
Description
6. Animations To retrieve an animation of the resources, use
the static method AnimationUtils.loadAnimation(int resource). Ex.
ImageView imageView = (ImageView) findViewById(R.id.imageview);
Animation animation = AnimationUtils.loadAnimation(this,
R.anim.hyperspace_jump); animation.setAnimationListener(new
AnimationListener() { @Override public void
onAnimationStart(Animation anim) { } @Override public void
onAnimationRepeat(Animation anim) { } @Override public void
onAnimationEnd(Animation anim) { } });
imageView.startAnimation(animation); View Animation -
Management
7. Animations A Property Animation changes a value of an object
for a specified period. You can specify the following variables:
Duration: the default is 300ms Interpolation: it specifies how to
calculate the value of the variable as a function of time
Repetition and behaviour: it specifies how many times the animation
should be repeated and whether normal or otherwise Set: you can
group animations to make them sequential or concurrent and start
them after a delay Frame refresh delay: you can specify how often
to refresh the view. The default is 10ms. Property Animation
8. Animations Ex. Animation with linear interpolation: Property
Animation Ex. Animation with linear interpolation:
9. Animations A Property Animation is realized with 3 basic
components: Animators: they contain the structure to create
animations, it is never used directly, but via its subclasses
Evaluators: they serve to define the method of calculation of the
object property to the animator Interpolators: they define how to
calculate the value of the object based on the time. They can be:
Linear Non-linear Property Animation
10. Animations 3 main subclasses: ValueAnimator: it contains
all the basic functionality for calculating a value of an object
ObjectAnimator: it extends ValueAnimator and simplifies the
functionality of the superclass AnimatorSet: provides a mechanism
for grouping animations Animator anim =
ValueAnimator.ofInt(values); anim.setEvaluator(evaluator);
anim.setInterpolator(interpolator); Property Animation -
Animators
11. Animations There are three main sub-classes and an
interface used: IntEvaluator: it calculates values for properties
of type int FloatEvaluator: it calculates values for properties of
type float ArgbEvaluator: it calculates values for properties of
type color represented by hexadecimal values TypeEvaluator: it's an
interface that allows you to create a custom evaluator Property
Animation - Evaluators
12. Animations There are 9 sub-classes and an interface used:
AccelerateDecelerateInterpolator AccelerateInterpolator
AnticipateInterpolator AnticipateOvershootInterpolator
BounceInterpolator CycleInterpolator DecelerateInterpolator
LinearInterpolator TimeInterpolator: interface to implement a
custom interpolator Property Animation - Interpolator
14. Animations It is a subclass of ValueAnimator. The object is
instantiated with static methods similar to those of the superclass
with the ability to define which properties should be animated:
ValueAnimator.ofInt(Object target, String property, int... values)
ValueAnimator.ofFloat(Object target, String property, float...
values) ValueAnimator.ofObject(Object target, String property,
TypeEvaluator evaluator, Object... values) Es. ObjectAnimator anim
= ObjectAnimator.ofFloat(view, "alpha", 0f, 1f);
anim.setDuration(1000); anim.start(); Property Animation
ObjectAnimator
15. Animations It includes animations and establishes the
sequence, simultaneity, and the delay. Es. AnimatorSet bouncer =
new AnimatorSet(); bouncer.play(bounceAnim).before(squashAnim1);
bouncer.play(squashAnim1).with(squashAnim2);
bouncer.play(squashAnim1).with(stretchAnim1);
bouncer.play(squashAnim1).with(stretchAnim2);
bouncer.play(bounceBackAnim).after(stretchAnim2); ValueAnimator
fadeAnim = ObjectAnimator.ofFloat(newBall, "alpha", 1f, 0f);
fadeAnim.setDuration(250); AnimatorSet animatorSet = new
AnimatorSet(); animatorSet.play(bouncer).before(fadeAnim);
animatorSet.start(); Property Animation AnimatorSet
16. Animations To access the events of the life cycle of the
animation there are 2 interfaces: Animator.AnimatorListener:
onAnimationStart() onAnimationEnd() onAnimationRepeat()
onAnimationCancel(): after this, onAnimationEnd() is still called
ValueAnimator.AnimatorUpdateListener: OnAnimationUpdate(): it is
invoked for each frame of the animation If you do not want to
implement all of the AnimationListener interfaces, you can use the
AnimationListenerAdapter class and implement only some methods.
Property Animation AnimationListeners
17. Animations As for the Animation View, you can declare the
Animator in xml file. To distinguish the Property Animation from
View Animation use the path /res/animator instead of /res/anim.
Property Animation XML
18. Animations To retrieve the animation from the resources you
can use the static method AnimatorInflater.loadAnimator()
AnimatorSet set = (AnimatorSet) AnimatorInflater.loadAnimator(
this, R.anim.property_animator); set.setTarget(view); set.start();
Property Animation XML
19. Animations Animated GIFs are not supported natively by
Android. To get an animation that plays subsequent images, use
Drawable Animations declared in /res/drawable using the node:
Drawable Animations
20. Animations This type of animation is regarded as a
Drawable, so, to use it, it recovers from the resources to view
image and set as background or layout xml or code. To start the
animation, use the method Animation.start() that can not be called
in Activity.onCreate (): AnimationDrawable rocketAnimation; public
void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState); setContentView(R.layout.main);
ImageView rocketImage = (ImageView)
findViewById(R.id.rocket_image);
rocketImage.setBackgroundResource(R.drawable.rocket_thrust);
rocketAnimation = (AnimationDrawable) rocketImage.getBackground();
} public boolean onTouchEvent(MotionEvent event) { if
(event.getAction() == MotionEvent.ACTION_DOWN) {
rocketAnimation.start(); return true; } return
super.onTouchEvent(event); } Drawable Animations
